Two retired comedians will take the stage in New York later this month at a fundraiser to benefit Illinois Rep. Tammy Duckworth, the leading Democrat running to challenge Republican Sen. Mark S. Kirk next fall.

David Letterman, who retired this year after three decades hosting the "The Late Show" on CBS, and Sen. Al Franken, who gained his own fame from his time as a writer and performer on NBC’s "Saturday Night Live," will headline the event to benefit the Duckworth Victory Fund. The fundraiser is described on an invitation as a night of “serious fun." To attend, a donor has to RSVP and send minimum contribution of at least $1,000 to the Duckworth Victory Fund – a sponsorship level labeled, “Kinda Serious.” To be “Totally Serious” and receive a ticket to an exclusive reception before the event, it gets totally expensive: The campaign has requested donors give $10,400 each.

Duckworth's host on Oct. 25 will be Alex Soros, the 29-year-old son of billionaire George Soros who launched his own political action committee, Bend The Arc PAC, earlier this year.

This will be the second time this year Franken has helped Duckworth raise money. During a Democratic Senatorial Campaign Committee retreat on Martha's Vineyard earlier this year, Franken organized a group of major donors to boost her campaign.

With a fundraising advantage and the endorsement of national Democratic groups such as the DSCC and EMILY's List, Duckworth — an Army combat veteran who was elected to the House in 2012 — has a serious advantage for her party's nod. She is being challenged in the primary by Andrea Zopp, a Chicago lawyer who is the former president of the Chicago Urban League.

Kevin Artl, Kirk's campaign manager, said Duckworth has had her own recent stumbles and accused her of reversing her position "on transparency in the Benghazi hearings."

Noting the "serious" sponsorship levels for the night of "serious" fun, Artl said Tuesday: "Named as one of Congress' least effective members, Rep. Duckworth clearly needs to get more 'serious' about her work."